基于叶轮设计的IS65型离心泵空化性能改进的研究

发布时间：2018-11-01 17:38

【摘要】：对于以液体为工作介质的离心泵来讲,空化是影响其正常运行的一种有害物理现象,而水泵空化性能的优劣又与叶轮的设计情况息息相关。本文运用流体力学相关知识,理论分析IS65型叶轮的水力性能,计算叶轮运转过程中,其内部流场中介质压力和流速的分布函数,找出引起介质空化的原因;指出IS65型叶轮中三圆弧柱面型叶片,存在不同相对运动流面出现相交的设计缺陷,这一缺陷导致叶轮运转时其流场内液态介质出现压力和流速波动,引起介质发生空化。在进行理论分析后,对安装IS65型叶轮的离心泵,进行额定流量工况下的整机数值模拟,采用Gambit软件对离心泵整机建立网格模型,再将建好的网格模型导入Fluent软件进行仿真模拟。仿真结果显示,叶轮流场中的最低绝对压力和最高绝对压力在模拟过程中,随时间变化多次出现振幅较大的压力脉动,其中最低绝对压力脉动时,其值都发生大幅度的减少,低于水介质的空化压力,诱使水介质发生空化,从液态变成汽态。因此,空化的发生与介质压力脉动有关,印证前面关于空化原因的理论分析。根据对安装IS65型叶轮离心泵出现空化的原因分析情况,采用以S2m流面为基础的三维设计法与速度系数法相结合的技术路线,保留叶轮的一些原设计参数,对IS65型叶轮进行反问题改进设计,主要改进叶片型线设计。对新设计出的叶片,分析其运转过程中,其内部流场中介质压力和流速参数的分布特性,根据流场中压力和流速的分布情况,判断新设计叶轮能够满足水泵使用性能要求。对新叶片进行理论分析之后,用Gambit软件对安装新叶轮的离心泵建立整机网格模型;再将水泵网格模型导入Fluent软件,进行额定流量工况下的整机数值模拟。模拟结果显示,新设计叶轮能够满足水泵的使用性能要求,叶轮流场中最低绝对压力和最高绝对压力随时间变化趋势比较平稳,没有出现振幅较大的压力脉动,在这样的压力场中水介质不易发生空化,水泵空化性能得到改善。最后,对全文的研究情况进行总结,指出分析计算过程中存在的不足之处,并对今后需要进一步开展研究的工作进行展望。
[Abstract]:For centrifugal pump with liquid as working medium cavitation is a harmful physical phenomenon which affects its normal operation and the cavitation performance of pump is closely related to the design of impeller. In this paper, the hydraulic performance of IS65 impeller is analyzed theoretically, the distribution function of medium pressure and velocity in the flow field of impeller is calculated, and the cause of medium cavitation is found out. It is pointed out that the three circular cylindrical blades in IS65 impeller have the design defect of intersecting different relative moving surfaces, which leads to the fluctuation of pressure and velocity of liquid media in the flow field of impeller, which causes cavitation of the medium. After theoretical analysis, the centrifugal pump installed with IS65 impeller was numerically simulated under rated flow condition. The grid model of centrifugal pump was established by Gambit software, and then the grid model was imported into Fluent software to simulate. The simulation results show that the minimum absolute pressure and the maximum absolute pressure in the impeller flow field vary with time many times, and the values of the lowest absolute pressure fluctuate greatly. The cavitation pressure below the water medium induces the water medium to cavitation from liquid to vapor. Therefore, the occurrence of cavitation is related to the pressure pulsation of the medium, which confirms the theoretical analysis of cavitation reasons. Based on the analysis of the cavitation of IS65 impeller centrifugal pump, the 3D design method based on S2m flow surface and the velocity coefficient method are adopted to preserve some original design parameters of impeller. The inverse problem design of IS65 impeller is improved, and the blade profile design is mainly improved. The distribution characteristics of medium pressure and velocity parameters in the internal flow field of the new designed blade are analyzed. According to the distribution of pressure and velocity in the flow field, the new designed impeller can meet the performance requirements of the pump. After theoretical analysis of the new blade, the whole machine grid model of centrifugal pump installed with new impeller is established by using Gambit software, and then the grid model of water pump is imported into Fluent software to carry out the numerical simulation of the whole machine under rated flow condition. The simulation results show that the new designed impeller can meet the performance requirements of the pump, and the minimum absolute pressure and the maximum absolute pressure in the impeller flow field change steadily with time, and there is no pressure pulsation with larger amplitude. In this pressure field, the cavitation of water is not easy and the cavitation performance of water pump is improved. Finally, the paper summarizes the research situation, points out the shortcomings in the process of analysis and calculation, and looks forward to further research work in the future.
【学位授予单位】：江西理工大学
【学位级别】：硕士
【学位授予年份】：2011
【分类号】：TH311

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